Stem cell hope for spinal injuries

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(CNN) -- Scientists in the U.S. have successfully used neural stem cells to regenerate damaged spinal cord tissue in mice, raising hopes that the technique could be used to treat disabilities caused by spinal cord injuries and human neurological disorders.

The team based at University of California at Irvine injected adult human neural stem cells into mice with limited mobility due to spinal injuries.

Within just nine days the mice showed marked improvement in their walking ability, according to the results of the study published in the journal, Proceedings of the National Academy of Sciences Early Edition.

The transplanted stem cells developed into cells that restored myelin, a fatty layer that insulates nerve fibres and is crucial for maintaining electrical conduction in the central nervous system.

A lack of myelin, caused by either disease or injury, can cause motor and sensory disorders such as multiple sclerosis, and paralysis.

The cells also formed new neurons that created synaptic connections with the mouse neurons.

"We set out to find whether these cells would be able to respond to the injury in an appropriate and beneficial way on their own," said Dr. Brian J. Cummings of UC Irvine, who led the study.

"We were excited to find that the cells responded to the damage by making appropriate new cells that could assist in the repair. This study supports the possibility that formation of new myelin and new neurons may contribute to recovery."

The mice that received the cells continued to show improvements in walking ability for four months after treatment.

When the human cells were killed with a toxin, the condition of the mice deteriorated, suggesting that the transplanted cells were the catalyst for their improved walking ability.

"This work is a promising first step and supports the need to study multiple stem cell types for the possibility of treating human neurological injury and disease," said UC Irvine's Dr. Aileen Anderson.